Bug 479393

Summary: (__int128_t)0>>128: unable to generate reloads
Product: [Fedora] Fedora Reporter: James Hogan <james>
Component: gcc4Assignee: Jakub Jelinek <jakub>
Status: CLOSED CURRENTRELEASE QA Contact:
Severity: medium Docs Contact:
Priority: low    
Version: 10   
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Hardware: x86_64   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2009-07-13 09:48:52 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Preprocessed source none

Description James Hogan 2009-01-09 09:40:55 UTC 
Created attachment 328530 [details]
Preprocessed source

Description of problem:

GCC crashes with "unable to generate reloads" when right-shifting an __int128_t  by 128 places.

Version-Release number of selected component (if applicable):

`gcc -v` gives:
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-cpu=generic --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.3.0 20080428 (Red Hat 4.3.0-8) (GCC) 

How reproducible:

always

Steps to Reproduce:
1. compile attached preprocessed source with gcc
  
Actual results:

`gcc bug_rh_173101_me.cc` says:

bug_rh_173101_me.cc: In function ‘int main()’:
bug_rh_173101_me.cc:4: warning: right shift count >= width of type
bug_rh_173101_me.cc:5: error: unable to generate reloads for:
(insn 7 6 8 2 bug_rh_173101_me.cc:4 (parallel [
            (set (reg:TI 0 ax [orig:58 D.2027 ] [58])
                (ashiftrt:TI (reg:TI 0 ax [61])
                    (const_int -128 [0xffffffffffffff80])))
            (clobber (reg:CC 17 flags))
        ]) 473 {*ashrti3_2} (expr_list:REG_DEAD (reg:TI 0 ax [61])
        (expr_list:REG_UNUSED (reg:CC 17 flags)
            (nil))))
bug_rh_173101_me.cc:5: internal compiler error: in find_reloads, at reload.c:374
4
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://bugzilla.redhat.com/bugzilla> for instructions.
Preprocessed source stored into /tmp/cc2LvvVE.out file, please attach this to yo
ur bugreport.

Expected results:

1) a sensible warning
2) code generated setting the __int128_t to 0 if right shifting more than bit-width.

Additional info:

see also bug #173101 where i originally mentioned this error. This bug has since apparently fixed the original problem but not the one provided by me.
Comment 1 Bug Zapper 2009-06-10 03:28:43 UTC 
This message is a reminder that Fedora 9 is nearing its end of life.
Approximately 30 (thirty) days from now Fedora will stop maintaining
and issuing updates for Fedora 9.  It is Fedora's policy to close all
bug reports from releases that are no longer maintained.  At that time
this bug will be closed as WONTFIX if it remains open with a Fedora 
'version' of '9'.

Package Maintainer: If you wish for this bug to remain open because you
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to a later Fedora version prior to Fedora 9's end of life.

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Comment 2 James Hogan 2009-06-10 08:40:22 UTC 
defect still present in updated fedora 10, gcc 4.3.2.

gcc -v:

Using built-in specs.
Target: x86_64-redhat-linux
Configured with: configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-cpu=generic --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC)

slightly different line number in error message, which is otherwise identical to above:

bug_rh_173101_me.cc:5: internal compiler error: in find_reloads, at reload.c:3767
Comment 3 Jakub Jelinek 2009-07-13 09:48:52 UTC 
Compiles just fine with gcc 4.4 and 4.5.